Maj Sjöwall is a Swedish author and translator. She is best known for the collaborative work with her partner Per Wahlöö on a series of ten novels about the exploits of Martin Beck, a police detective in Stockholm. In 1971, the fourth of these books, The Laughing Policeman (a translation of Den skrattande polisen, originally published in 1968) won an Edgar Award from the Mystery Writers of America for Best Novel.They also wrote novels separately.
One blustery November evening someone guns down nine occupants of a Stockholm bus, one of them a colleague of Martin Beck. It appeared to be a random killing, but Beck's investigation would lead him to a different conclusion.